Radiation detection device

ABSTRACT

There is provided a radiation detection device capable of realizing both suppression of deformation and weight reduction of a support plate to which a radiation detection panel is fixed. A radiation detection device includes: a radiation detection panel that detects radiation; a support plate which is formed of a MgLi alloy and to which the radiation detection panel is fixed in contact with the support plate; a plurality of tubular support posts that are formed in contact with a surface of the support plate not facing the radiation detection panel; and a housing (rear surface member) in which the radiation detection panel, the support plate, and the support posts are housed and which is disposed in contact with the support posts.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese PatentApplication No. 2018-184312 filed Sep. 28, 2018, the disclosure of whichis incorporated by reference herein.

BACKGROUND Technical Field

The present invention relates to a radiation detection device.

Related Art

JP2018-115899A discloses a configuration in which at least one alloymaterial selected from an aluminum alloy and a magnesium alloy is usedas a metal support plate for fixing a circuit board in order to providea portable X-ray image detection device excellent in lightness.

JP2004-321568A discloses a configuration in which a radiation imagedetection panel is fixed to a base formed of an aluminum alloy, amagnesium alloy, or the like in order to protect a radiation imagecapturing apparatus from vibration, impact, and the like duringtransportation.

SUMMARY

The radiation detection devices disclosed in JP2018-115899A andJP2004-321568A may be attached to the imaging table in the imaging room,or may be taken out of the imaging room and inserted between the bed inthe patient's room and the patient. For this reason, it is preferable toreduce the weight of the devices as much as possible in order tofacilitate portability.

On the other hand, in the radiation detection devices, a local load islikely to be applied to, for example, the radiation receiving surfacedue to their use form. A radiation detection panel is stored inside theradiation detection device. In order to protect the radiation detectionpanel, it is preferable that a support plate to which the radiationdetection panel is fixed is not deformed as much as possible by externalload.

However, in the configuration using an aluminum alloy or a magnesiumalloy as a support plate as in JP2018-115899A and JP2004-321568A, it isdifficult to realize both suppression of deformation and weightreduction.

Therefore, it is an object of the invention to provide a radiationdetection device capable of realizing both suppression of deformationand weight reduction of a support plate to which a radiation detectionpanel is fixed.

In order to achieve the aforementioned object, a radiation detectiondevice according to the invention comprises: a radiation detection panelthat detects radiation; a support plate which is formed of a MgLi alloyand to which the radiation detection panel is fixed in contact with thesupport plate; a plurality of tubular support posts that are formed incontact with a surface of the support plate not facing the radiationdetection panel; and a housing in which the radiation detection panel,the support plate, and the support posts are housed and which isdisposed in contact with the support posts.

In the radiation detection device according to the invention, thesupport posts are polygonal, and at least some of the support postsadjacent to each other are disposed such that sides of the support postsface each other.

In the radiation detection device according to the invention, each ofthe support posts is formed so as to have an axial direction along anout-of-plane direction of the support plate.

In the radiation detection device according to the invention, athickness of each of the support posts gradually increases from a distalend to a root portion near the support plate.

In the radiation detection device according to the invention, thesupport posts are formed integrally with the support plate using thesame material as the support plate.

In the radiation detection device according to the invention, areinforcing rib is bridged between the support posts so as to be incontact with the surface of the support plate not facing the radiationdetection panel.

In the radiation detection device according to the invention, both endportions of the reinforcing rib are formed such that thicknesses thereofalong axial directions of the support posts gradually increase towardthe support posts.

In the radiation detection device according to the invention, an innerreinforcing rib is bridged between inner walls of the support post.

In the radiation detection device according to the invention, the innerreinforcing rib is disposed on an extension line of the reinforcing rib.

In the radiation detection device according to the invention, an outerperipheral portion of the support plate is bonded to the housing.

In the radiation detection device according to the invention, aframe-shaped outer peripheral portion reinforcing rib is provided in theouter peripheral portion of the support plate, and the outer peripheralportion reinforcing rib is bonded to the housing.

In the radiation detection device according to the invention, thehousing comprises: a mounting rib to which the outer peripheral portionof the support plate is attached; a connection rib to which the mountingrib is connected; and an outer rib and an inner rib that are connectedto each other by the connection rib and are formed along an outer edgeof the housing.

In the radiation detection device according to the invention, aplurality of tubular support posts are formed in contact with thesurface of the support plate not facing the radiation detection panel,and the support posts are disposed in contact with the housing.

Here, the support plate is formed of a magnesium lithium alloy (MgLialloy). The MgLi alloy has a smaller specific gravity than, for example,a magnesium alloy (Mg alloy) or an aluminum alloy (Al alloy). For thisreason, by using the MgLi alloy as the support plate, the weight can bereduced as compared with the Mg alloy or the like.

The MgLi alloy has a smaller Young's modulus and a lower stiffness thanthe Mg alloy, the Al alloy, and the like. In the invention, in a casewhere the radiation detection device is pressed from the outside at thetime of use of the radiation detection device and a load in theout-of-plane direction acts on the radiation detection panel, the loadreceived by the support plate is transmitted to the housing by thesupport posts. Therefore, the support plate is hardly deformed. Inaddition, by forming the support posts in a tubular shape, bothsuppression of deformation and weight reduction of the support plate canbe realized.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary Embodiments of the present invention will be described indetail with reference to the following figures, wherein:

FIG. 1 is a perspective view showing a radiation detection deviceaccording to the present embodiment.

FIG. 2 is an exploded side sectional view showing a state in which theradiation detection device according to the present embodiment isdisassembled.

FIG. 3 is a side sectional view showing the radiation detection deviceaccording to the present embodiment.

FIG. 4 is a front view showing a rear surface member in the radiationdetection device according to the present embodiment.

FIG. 5 is a front view showing a support plate in the radiationdetection device according to the present embodiment.

FIG. 6 is a front view showing a radiation detection panel in theradiation detection device according to the present embodiment.

FIG. 7 is a front view showing a control substrate in the radiationdetection device according to the present embodiment.

FIG. 8 is a front view showing a modification example in which a trussstructure is formed by reinforcing ribs of the rear surface member inthe radiation detection device according to the present embodiment.

FIG. 9 is a front view showing a modification example in which an innerrib and an outer rib of the rear surface member in the radiationdetection device according to the present embodiment are formed so as tohave the same thickness.

FIG. 10 is a perspective view showing a modification example in which anopening portion for battery insertion is provided only on the short sidein the radiation detection device according to the present embodiment.

FIG. 11 is a perspective view showing a modification example in whichtwo opening portions for battery insertion are provided on the same sidesurface in the radiation detection device according to the presentembodiment.

FIG. 12 is a perspective view showing a modification example in which anopening portion for battery insertion is provided on the back surface ofthe rear surface member in the radiation detection device according tothe present embodiment.

FIG. 13 is a cross-sectional view showing a modification example inwhich a support post formed on the support plate in the radiationdetection device according to the present embodiment is formed such thatthe thickness of the support post gradually increases from a distal endportion thereof toward the support plate.

FIG. 14 is a cross-sectional view showing a modification example inwhich a support post formed on the support plate in the radiationdetection device according to the present embodiment is formed such thatthe thickness of the support post gradually increases from a centralportion in the axial direction toward the support plate.

FIG. 15 is a cross-sectional view showing a modification example inwhich an end portion of a reinforcing rib formed on the support plate inthe radiation detection device according to the present embodiment isformed such that the thickness of the end portion gradually increasestoward the support plate.

FIG. 16 is a cross-sectional view showing a modification example inwhich a reinforcing rib is formed inside the support post formed on thesupport plate in the radiation detection device according to the presentembodiment.

FIG. 17 is a cross-sectional view showing a modification example inwhich the support post and the support plate in the radiation detectiondevice according to the present embodiment are formed as separatebodies.

FIG. 18 is a cross-sectional view showing a modification example inwhich the support post and the support plate in the radiation detectiondevice according to the present embodiment are formed as separate bodiesand the axial direction of the support post is a direction along thein-plane direction of the support plate.

FIG. 19 is a cross-sectional view showing a modification example inwhich the support post is formed integrally with a bottom plate of therear surface member in the radiation detection device according to thepresent embodiment.

FIG. 20 is an enlarged plan view showing a modification example in whichthe support posts in the radiation detection device according to thepresent embodiment are formed as only support posts having the sameshape.

FIG. 21 is an enlarged plan view showing a modification example in whichthe support posts in the radiation detection device according to thepresent embodiment are formed in an octagonal shape.

DETAILED DESCRIPTION

Radiation Detection Device

FIG. 1 is a schematic perspective view of a radiation detection device10 according to an embodiment of the invention. The radiation detectiondevice 10 is an electronic cassette having an approximately rectangularshape in a plan view, and is driven by a battery 100 mounted on ahousing 12 configured to include a front surface member 20 and a rearsurface member 30.

The planar size of the housing 12 is, for example, a size according tothe international standard ISO4090: 2001 similar to a half size (383.5mm×459.5 mm) film cassette or imaging plate (IP) cassette. Therefore,the radiation detection device 10 can also be used in a state in whichthe radiation detection device 10 is attached to an imaging table for afilm cassette or an IP cassette.

The battery 100 is mounted on the radiation detection device 10 by beinginserted into opening portions 30A and 30B formed at the centralportions of two adjacent sides of the rear surface member 30 having anapproximately rectangular shape in a plan view. The radiation detectiondevice 10 is driven in a state in which the battery 100 is mounted in atleast one of the opening portions 30A and 30B.

The opening portion 30A is an opening portion formed at the centralportion of a side surface (short side) along the Y direction shown inFIG. 1 in the radiation detection device 10, and the opening portion 30Bis an opening portion formed at the central portion of a side surface(long side), which is adjacent to the side surface on which the openingportion 30A is formed and extends along the X direction perpendicular tothe Y direction.

The front surface member 20 attached to the rear surface member 30 isconfigured to include an approximately rectangular transmission plate22. The transmission plate 22 is formed of, for example, a carbonmaterial having a high X-ray transmittance. Radiation (X-rays P in thepresent embodiment) is incident from a direction approximatelyperpendicular to the in-plane direction of the transmission plate.

The front surface member 20 and the rear surface member 30 are formed bydie casting using a Mg alloy in the present embodiment. However, thematerial and manufacturing method of the front surface member 20 and therear surface member 30 are not limited thereto, and the front surfacemember 20 and the rear surface member 30 can be molded using variousmetals, resins, and the like.

FIG. 2 is an exploded cross-sectional view of the housing 12 (refer toFIGS. 1 and 3). As shown in FIG. 2, a radiation detection panel 40, asupport plate 50 to which the radiation detection panel 40 is attached,and a control substrate 60 for controlling the radiation detection panel40 are provided inside the housing 12 so as to be interposed between thefront surface member 20 and the rear surface member 30.

The radiation detection device 10 shown in FIG. 3 is formed byassembling the front surface member 20, the rear surface member 30, theradiation detection panel 40, the support plate 50, the controlsubstrate 60, the battery 100, and the like (refer to FIG. 1).

In FIGS. 2 and 3, the configuration of the support plate 50 is shown ina simplified manner. That is, the support plate 50 shown in FIGS. 2 and3 schematically shows the configuration of the support plate 50 in whicha support post 54, a reinforcing rib 56B, and a protection rib 56D to bedescribed later are omitted.

Back Member-Double Frame

The rear surface member 30 is formed to comprise a double frame 32 (anouter rib 32A and an inner rib 32B) and a bottom plate 34. As shown inFIG. 4, the double frame 32 is formed in a rectangular frame shape alongthe X and Y directions described above, and as shown in FIG. 2, thebottom plate 34 is fitted onto the bottom surface. The bottom plate 34is fixed to the double frame 32 using a screw or the like.

In the double frame 32, the inner rib 32B for reinforcing a rectangularopening end into which the bottom plate 34 is fitted is erected towardthe front surface member 20. The double frame 32 is gradually raisedfrom the bottom surface onto which the bottom plate 34 is fitted to theouter edge portion in a direction of the front surface member 20, andthe raised portion is the outer rib 32A.

The rising height H1 of the outer rib 32A is set to be larger than therising height H2 of the inner rib 32B, and the thickness W1 of the outerrib 32A is set to be larger than the thickness W2 of the inner rib 32B.As an example, the thickness W1 is about 4 mm to 5 mm, and the thicknessW2 is about 0.8 mm. In the present embodiment, the outer rib 32A isformed to be thicker than the inner rib 32B over the entirecircumference. However, the embodiment of the invention is not limitedthereto, and the outer rib 32A may be formed partially thinner than theinner rib 32B. In other words, the inner rib 32B may be formed partiallythicker than the outer rib 32A.

A packing (not shown) formed of resin is disposed between the frontsurface member 20 and the surface of the outer rib 32A, which faces thefront surface member 20, in the rear surface member 30 and is compressedbetween the front surface member 20 and the rear surface member 30, sothat the internal space formed between the front surface member 20 andthe rear surface member 30 is a watertight space.

FIG. 4 shows a plan view of the rear surface member 30 (a state in whichthe rear surface member 30 is viewed from the incidence direction of anX-ray P shown in FIG. 1). As shown in FIG. 4, the outer rib 32A isformed along the outer edge of the rear surface member 30 in a frameshape in which each side extends along the X and Y directions. On theinner side of the outer rib 32A, the inner rib 32B is formed in a frameshape along the outer rib 32A.

It is assumed that “along” in the invention includes not only a state inwhich the outer rib 32A and the inner rib 32B are disposed in parallelso as to be spaced apart from each other but also a state in which theouter rib 32A and the inner rib 32B are disposed in parallel so as to bein contact with each other. In addition, the outer rib 32A and the innerrib 32B do not need to be strictly parallel, and a case where there istwisting due to manufacturing variations or a state in which at leastone of the outer rib 32A or the inner rib 32B is disposed in a zigzag orwave shape is also included.

The “frame shape” in the invention indicates a state in which the outerrib 32A is disposed in a portion, which covers the length of half ormore of the circumferential length, in the outer edge portion of therear surface member 30. The outer rib 32A does not need to becontinuous, and may have an intermittent portion. In addition, as willbe described later, an opening portion by a through hole may be formedin the outer rib 32A. The same applies to the inner rib 32B.

Through holes 32AA and 32AB are formed in the outer rib 32A, so that thebattery 100 (refer to FIG. 1) can be inserted thereinto. The inner rib32B is not formed on the inner side in the insertion direction of thebattery 100 in the through holes 32AA and 32AB. In other words, in theinner rib 32B, intermittent portions 32BA and 32BB are formed on theinner sides of the through holes 32AA and 32AB in the outer rib 32A.

The opening portion 30A is formed by the through hole 32AA andintermittent portion 32BA, and the opening portion 30B is formed by thethrough hole 32AB and intermittent portion 32BB. The through holes 32AAand 32AB and the intermittent portions 32BA and 32BB are examples of the“opening portion” in the invention.

Back Member-Connection Rib

As shown in FIG. 4, a plurality of connection ribs 36 are bonded to theouter rib 32A and the inner rib 32B, and the outer rib 32A and the innerrib 32B are connected to each other by the connection ribs 36. Theconnection rib 36 extends in a direction approximately perpendicular tothe outer rib 32A and the inner rib 32B. In the following description,the connection rib 36 extending from the corner portion of the outer rib32A toward the inner rib 32B is referred to as a corner portionconnection rib 36A. In addition, the connection ribs 36 formed at bothends of the opening portions 30A and 30B are referred to as openingconnection ribs 36B.

The “corner portion” of the outer rib 32A refers to a portion that iscloser to the outer rib 32A along the X direction than a center line CL1along the X direction of the rear surface member 30 and closer to theouter rib 32A along the Y direction than a center line CL2 along the Ydirection of the rear surface member 30. In addition, the “centralportion” of the outer rib 32A refers to a portion other than the “cornerportion” described above, which is a portion including the center linesCL1 and CL2.

A plurality of corner portion connection ribs 36A are formed for eachcorner portion, and extend from the corner portion of the outer rib 32Atoward the inner rib 32B in a direction crossing the X and Y directions.In the inner rib 32B, an oblique portion 32C extending in a directionapproximately perpendicular to the corner portion connection rib 36A isformed in a portion facing the corner portion of the outer rib 32A. Inother words, the inner rib 32B is formed in a frame shape in which apart of the rectangular corner portion is chamfered, and the obliqueportion 32C connected such that the corner portion connection rib 36A isperpendicular thereto is formed in the chamfered portion.

The oblique portion 32C is formed in an end portion of a side, which isa side along the short side of the radiation detection device 10 (thatis, a side along the Y direction) and on which the opening portion 30Ais formed, among the sides of the inner rib 32B.

On the other hand, a side, which is a side along the short side of theradiation detection device 10 (that is, a side along the Y direction)and on which the opening portion 30A is not formed, among the sides ofthe inner rib 32B is disposed such that the separation distance from theouter rib 32A is larger than those of the other sides.

The opening connection rib 36B connects the outer rib 32A and the innerrib 32B at both end portions of the intermittent portions 32BA and 32BBin the inner rib 32B. A mounting rib 38 that forms a mounting hole forfixing the support plate 50 (refer to FIG. 2) is connected to theopening connection rib 36B.

A plurality of mounting ribs 38 are provided, and are also connected tothe connection rib 36 disposed in the vicinity of the corner portionconnection rib 36A in addition to the opening connection rib 36B. Themounting rib 38 is also connected to the side of the inner rib 32B wherethe separation distance from the outer rib 32A is larger than those ofthe other sides. In addition, “vicinity of the corner portion connectionrib 36A” refers to a portion included in the “corner portion” describedabove.

Support Plate

FIG. 5 shows a plan view of the support plate 50 (a state in which thesupport plate 50 is viewed from a direction opposite to the incidencedirection of the X-ray P shown in FIG. 1). That is, a surface oppositeto the surface to which the radiation detection panel 40 shown in FIG. 2is attached is shown.

The support plate 50 is formed using a MgLi alloy in which the mixingratio (mass percentage) of lithium (Li) to magnesium (Mg) is 9%.

The mixing ratio of lithium (Li) is not limited to 9%, and may be 1.5%or more and 14% or less. In a case where the mixing ratio is less than1.5%, it is difficult to obtain the weight reduction effect. That is,between a MgLi alloy and a Mg alloy having the same stiffness, theweight of the Mg alloy can be reduced. In a case where the mixing ratiois larger than 14%, it is necessary to consider corrosion resistance.

A support post 52 is formed integrally with the support plate 50, and asshown in FIG. 2, is formed in a tubular shape having an axial directionalong the out-of-plane direction (a direction perpendicular to thein-plane direction, that is, a normal direction) of the support plate50. The wall surface of the support post 52 is formed perpendicular tothe support plate 50.

As shown in FIG. 3, in a state in which the housing 12, the radiationdetection panel 40, and the support plate 50 are assembled, thetransmission plate 22 is disposed in contact with the radiationdetection panel 40. In addition, the support post 52 and the supportpost 54 to be described later are disposed in contact with the bottomplate 34 in the rear surface member 30.

“Disposed in contact” includes a state in which there is a gap thatallows the support posts 52 and 54 to be in contact with the bottomplate 34 in a case where the transmission plate 22 is pressed from theoutside at the time of use of the radiation detection device 10.Although described in detail later, a case where the support post andthe bottom plate are integrally formed is included.

As shown in FIG. 5, the support posts 52 are formed in an approximatelyregular hexagonal shape, and are disposed at predetermined intervals ina plan view. More specifically, the center of the support post 52 isdisposed on the grid point of the equilateral triangle grid filling theplane. Each apex in the hexagonal support post 52 is chamfered in acurvilinear shape and disposed on the side of a triangle forming theequilateral triangle grid.

Between the support posts 52, the hexagonal support post 54 in whichadjacent sides have different lengths is disposed. More specifically,the center of the support post 54 is disposed on the center of gravityof the triangle forming the above-described equilateral triangle grid.In the support post 54, a short side 54A and a long side 54B are formedso as to be alternately adjacent to each other, the short side 54A facesa side 52A of the support post 52, and the long side 54B faces the longside 54B of the adjacent support post 54. In the present embodiment, thesides 52A of the support posts 52 adjacent to each other are notdisposed so as to face each other. In the invention, “at least some ofthe support posts are disposed such that their sides face each other”may include support posts whose sides are not disposed so as to faceeach other as described above.

In addition, between the support posts 52 adjacent to each other, thereinforcing rib 56A is formed along the equilateral triangle griddescribed above. In addition, the reinforcing rib 56B is formed betweenthe support post 52 and the support post 54 adjacent to each other andbetween the support posts 54 adjacent to each other.

Furthermore, a frame-shaped outer peripheral portion reinforcing rib 56Cis formed along the outer periphery of the support plate 50 so as tosurround the support posts 52 and 54 and the reinforcing ribs 56A and56B. A protruding portion 58 is formed in the outer peripheral portionreinforcing rib 56C. The protruding portion 58 is formed at a positioncorresponding to the mounting hole formed by the mounting rib 38 of therear surface member 30 described above. By inserting the protrudingportion 58 into the mounting hole and bonding these to each other, outerperipheral portions of the rear surface member 30 and the support plate50 are bonded to each other.

Furthermore, the protection rib 56D is formed at positions correspondingto the opening portions 30A and 30B in the rear surface member 30. Theprotection rib 56D divides the outer peripheral portion reinforcing rib56C, and is disposed so as to surround the battery 100 (refer to FIG. 1)inserted into the opening portions 30A and 30B.

Radiation Detection Panel

The radiation detection panel 40 is a quadrilateral flat plate havingfour sides at the outer edge in a plan view. As shown in FIG. 6, theradiation detection panel 40 includes a thin film transistor (TFT)active matrix substrate (TFT substrate) 47 in which a thin filmtransistor 48A and a capacitor 48B are formed on an insulatingsubstrate. On the TFT substrate 47, a scintillator (not shown) forconverting incident X-rays into light is disposed. On the TFT substrate47, a sensor unit 48C that generates electric charges by incidence oflight converted by the scintillator is formed.

On the TFT substrate 47, a plurality of pixels 48 each including thesensor unit 48C, the capacitor 48B, and the thin film transistor 48A areprovided in a two-dimensional manner in a predetermined direction(horizontal direction in FIG. 6=row direction) and a direction (verticaldirection in FIG. 6=column direction) crossing the predetermineddirection.

A plurality of gate lines 42B for turning on and off each thin filmtransistor 48A and a plurality of data lines 42A for reading outelectric charges through the thin film transistor 48A in the ON stateare provided in the radiation detection panel 40. The gate lines 42B andthe data lines 42A extend in a direction crossing each other.

A plurality of connectors 44A for line connection are provided side byside on one end side of the data line 42A, and a plurality of connectors44B are provided side by side on one end side of the gate line 42B.

One end of a flexible cable 46A is connected to the connector 44A, andone end of the flexible cable 46B is connected to the connector 44B.

Control Substrate

As shown in FIG. 7, a signal processing unit 62A, a gate line driver62B, an image memory 62C, a controller 62D, a wireless communicationunit (not shown), and the like are provided on the control substrate 60.

Each gate line 42B of the TFT substrate 47 is connected to the gate linedriver 62B through the flexible cable 46B, and each data line 42A of theTFT substrate 47 is connected to the signal processing unit 62A throughthe flexible cable 46A.

The gate line driver 62B and the signal processing unit 62A are disposedalong two adjacent sides of the support plate 50, and are directlybonded to the support plate 50. That is, the gate line driver 62B andthe signal processing unit 62A are disposed so as to be in directcontact with the support plate 50 without using a mount member, such asa resin.

The gate line driver 62B and the signal processing unit 62A are attachedto a side of the support plate 50 different from the side on which theprotection rib 56D for protecting the battery 100 is provided. The imagememory 62C and the controller 62D are attached at positions that do notinterfere with the support posts 52 and 54.

The arrangement of the gate line driver 62B, the signal processing unit62A, the image memory 62C, and the controller 62D shown in FIG. 7 is anexample, and can be appropriately changed according to the shapes or thearrangement of the support posts. In other words, the arrangement of thesupport posts can be appropriately adjusted according to the sizes orthe shapes of the gate line driver 62B, the signal processing unit 62A,and the image memory 62C.

The thin film transistors 48A of the TFT substrate 47 are sequentiallyturned on row by row by a signal supplied from the gate line driver 62Bthrough the gate line 42B. The electric charges read out by the thinfilm transistor 48A that is turned on are transmitted as an electricsignal through the data line 42A and input to the signal processing unit62A. As a result, the electric charges are sequentially read out row byrow, and a two-dimensional radiation image can be acquired.

Although not shown, the signal processing unit 62A includes a sample andhold circuit and an amplification circuit for amplifying the inputelectric signal for each data line 42A, and the electric signaltransmitted through each data line 42A is amplified by the amplificationcircuit and then held in the sample and hold circuit. In addition, amultiplexer and an analog/digital (A/D) converter are connected in orderto the output side of the sample and hold circuit. The electric signalsheld in the respective sample and hold circuits are sequentially(serially) input to the multiplexer and converted into digital imagedata by the A/D converter.

The image memory 62C is connected to the signal processing unit 62A, andthe image data output from the A/D converter of the signal processingunit 62A is sequentially stored in the image memory 62C. The imagememory 62C has a storage capacity capable of storing image data of apredetermined number of sheets, and image data obtained by imaging issequentially stored in the image memory 62C each time a radiation imageis captured.

The image memory 62C is connected to the controller 62D. The controller62D is a microcomputer, and comprises a central processing unit (CPU), amemory including a read only memory (ROM) and a random access memory(RAM), and a non-volatile storage unit including a flash memory and thelike. The controller 62D controls the overall operation of the radiationdetection device 10.

A wireless communication unit (not shown) is connected to the controller62D. The wireless communication unit complies with a wireless local areanetwork (LAN) standard represented by Institute of Electrical andElectronics Engineers (IEEE) 802.11a/b/g or the like, and controlstransmission of various kinds of information to and from an externalapparatus by wireless communication. The controller 62D can wirelesslycommunicate with an external apparatus, such as a console that controlsthe entire radiation imaging, through the wireless communication unit,so that it is possible to transmit and receive various kinds ofinformation to and from the console.

The various circuits or elements (the gate line driver 62B, the signalprocessing unit 62A, the image memory 62C, the wireless communicationunit, or the microcomputer functioning as the controller 62D) operatewith the power supplied from the battery 100. In FIG. 7, wirings forconnecting the battery 100 to various circuits or elements are notshown.

In the radiation detection device 10 according to the embodiment of theinvention, as shown in FIGS. 2 and 5, a plurality of tubular supportposts 52 and 54 are formed in contact with the surface of the supportplate 50 not facing the radiation detection panel 40, and the supportposts 52 and 54 are disposed in contact with the bottom plate 34 of thehousing 12. In addition, “in contact with” includes a state of beingformed integrally with the support plate 50 as in the case of thesupport posts 52 and 54.

Here, the support plate 50 is formed of a MgLi alloy. The MgLi alloy hasa smaller specific gravity than, for example, a Mg alloy or an Al alloy.For this reason, by using the MgLi alloy as the support plate 50, theweight can be reduced as compared with the Mg alloy or the like.

The MgLi alloy has a smaller Young's modulus and a lower stiffness thanthe Mg alloy, the Al alloy, and the like. In the present embodiment, ina case where the radiation detection device 10 is pressed from theoutside at the time of use of the radiation detection device 10 and aload in the out-of-plane direction acts on the radiation detection panel40, the load received by the support plate 50 is transmitted to thehousing 12 by the support posts 52 and 54. Therefore, the support plate50 is hardly deformed. In addition, by forming the support posts 52 and54 in a tubular shape, both suppression of deformation of the supportplate 50 and reduction in the weight of the support plate 50 can berealized.

In the radiation detection device 10, the support posts 52 and 54 areformed in a hexagonal shape, and the support posts 52 and 54 adjacent toeach other are disposed such that the side 52A and the short side 54Aface each other. In addition, the support posts 54 adjacent to eachother are disposed such that the long sides 54B face each other.

Therefore, the supporting force of the support posts 52 and 54 can beincreased. That is, in a case where the radiation detection device 10 ispressed from the outside at the time of use of the radiation detectiondevice 10 and a load in the out-of-plane direction acts on a portion ofthe radiation detection panel 40 between the support posts 52 and 54,the load is transmitted to the support posts 52 and 54.

In this case, since the load is supported by the side 52A and the shortside 54A, the internal stress generated in the support posts 52 and 54is dispersed, for example, in the case of supporting the support posts52 and 54 at the apex of the hexagonal shape. Therefore, the supportingforce of the support posts 52 and 54 is increased.

In the radiation detection device 10, the support posts 52 and 54 areformed along a direction perpendicular to the in-plane direction, andthe axial direction of each of support posts 52 and 54 is theout-of-plane direction of the support plate 50. Therefore, thesupporting force against the external force from the directionperpendicular to the support plate 50 and the transmission plate 22 ishigh.

In the radiation detection device 10, the support posts 52 and 54 aremolded integrally with the support plate 50. Therefore, the loadreceived by the support plate 50 is easily transmitted to the supportposts 52 and 54. In addition, for example, compared with a case wherethe support posts 52 and 54 and the support plate 50 are bonded to eachother, the followability to the out-of-plane deformation of the supportplate 50 is high, and the durability is high.

In the radiation detection device 10, the reinforcing ribs 56A and 56Bin contact with the support plate 50 are bridged between the supportposts 52, between the support posts 54, and between the support posts 52and 54. Therefore, in a case where the load in the out-of-planedirection acts between the support posts 52, between the support posts54, and between the support posts 52 and 54, the load is transmitted tothe reinforcing ribs 56A and 56B and further transmitted to the supportposts 52 and 54.

As described above, since the load is once transmitted to thereinforcing ribs 56A and 56B before the load is transmitted to thesupport posts 52 and 54, the reinforcing ribs 56A and 56B function asbeam members to suppress the out-of-plane deformation of the supportplate 50.

In the radiation detection device 10, as shown in FIGS. 2 and 3, theradiation detection panel 40 is disposed between the front surfacemember 20 and the rear surface member 30. The outer rib 32A is formedalong the outer edge of the rear surface member 30, and the inner rib32B is formed on the inner side of the outer rib 32A. Therefore, thestiffness of the rear surface member 30 is higher than that in astructure that does not have either the inner rib 32B or the outer rib32A or a structure that does not have any of the inner rib 32B and theouter rib 32A. For this reason, for example, even in a case where animpact at the time of drop is applied to the radiation detection device10, the rear surface member 30 is hardly deformed. Accordingly, theradiation detection panel 40 is protected.

In the radiation detection device 10, as shown in FIG. 4, the outer rib32A and the inner rib 32B are formed in a frame shape. For this reason,the rear surface member 30 is less likely to be distorted as comparedwith a case where at least one of the outer rib or the inner rib isformed, for example, only in a corner portion of the rear surface member30 or only on a side along the X direction or the Y direction.Therefore, the effect of protecting the radiation detection panel 40 ishigh.

In the radiation detection device 10, the outer rib 32A is formedthicker than the inner rib 32B. Therefore, for example, compared with acase where the thickness of the inner rib is larger than that of theouter rib or a case where the inner rib and the outer rib have the samethickness, the outer rib to which the impact from the outside isdirectly applied is less likely to be deformed. As a result, deformationof the rear surface member 30 due to impact can be efficientlysuppressed.

In the radiation detection device 10, the outer rib 32A and the innerrib 32B are connected to each other by the connection rib 36. Therefore,the impact received by the outer rib 32A can be transmitted to the innerrib 32B through the connection rib 36. As a result, compared with aconfiguration without the connection rib 36, the effect of improving thestiffness of the rear surface member 30 by the inner rib 32B can beenhanced.

A part of the connection rib 36 is the corner portion connection rib 36Aextending from the corner portion of the outer rib 32A toward the innerrib 32B, and the oblique portion 32C in the inner rib 32B is formed soas to be perpendicular to the corner portion connection rib 36A.

Therefore, an impact C applied to the corner portion of the outer rib32A is transmitted to the oblique portion 32C through the corner portionconnection rib 36A. In this case, the corner portion connection rib 36Acan function as a compression member between the outer rib 32A and theoblique portion 32C to resist an impact.

In a case where the impact C is applied to the corner portion of theouter rib 32A, a tensile force T acts on a corner portion adjacent tothe corner portion to which the impact is applied. In this case, thecorner portion connection rib 36A can function as a tension memberbetween the outer rib 32A and the oblique portion 32C to suppress thedeformation of the rear surface member 30.

As shown in FIGS. 2 and 3, the radiation detection device 10 comprisesthe support plate 50 for supporting the radiation detection panel 40,and the protruding portion 58 in the support plate 50 is inserted intothe mounting hole formed by the mounting rib 38 in the rear surfacemember 30 and bonded thereto. Therefore, the rear surface member 30 isstiffened by the support plate 50 that is a plate material, and sheardeformation along the in-plane direction of the support plate 50 issuppressed. In addition, bending deformation along the out-of-planedirection of the support plate 50 is suppressed.

The support plate 50 is bonded to the rear surface member 30 at thecorner portion of the rear surface member 30. Therefore, for example,compared with a case where the support plate 50 is bonded to the rearsurface member 30 at a portion other than the corner portion, the areaof a portion surrounded by the bonded portion is increased. As a result,the effect of improving the stiffness of the rear surface member 30 isenhanced.

As a method of bonding the support plate 50 and the rear surface member30 to each other, in addition to the method of inserting the protrudingportion 58 into the mounting hole formed by the mounting rib 38, variousmethods such as screwing, welding, and bonding can be adopted. Materialsof the support plate 50 and the rear surface member 30 can be freelyselected, and any bonding method suitable for the materials can beselected.

Furthermore, as shown in FIG. 5, a reinforcing rib 56 is formed on thesupport plate 50. The protruding portion 58 is formed in the outerperipheral portion reinforcing rib 56C formed in a frame shape among thereinforcing ribs 56. The support plate 50 is fixed to the rear surfacemember 30 by the protruding portion 58. Therefore, the rear surfacemember 30 has a triple frame structure of the outer rib 32A, the innerrib 32B, and the outer peripheral portion reinforcing rib 56C in a statein which the rear surface member 30 is bonded to the support plate 50.As a result, the effect of suppressing the deformation of the rearsurface member 30 is further enhanced.

In a portion surrounded by the outer peripheral portion reinforcing rib56C in the support plate 50, the reinforcing ribs 56A and 56B and thesupport posts 52 and 54 are connected to each other. Therefore, comparedwith the configuration without the reinforcing ribs 56A and 56B and thesupport posts 52 and 54, the outer peripheral portion reinforcing rib56C is less likely to be deformed. As a result, the effect ofsuppressing the deformation of the rear surface member 30 is furtherenhanced.

Since the support plate 50 and the rear surface member 30 are bonded toeach other as described above, the rear surface member 30 is reinforced,and the support plate 50 is similarly reinforced. That is, in thesupport plate 50, the protruding portion 58 in the outer peripheralportion reinforcing rib 56C formed in the outer peripheral portion ofthe support plate 50 is fixed to the rear surface member 30. Therefore,the stiffness of the support plate 50 is higher than that in aconfiguration in which the support plate 50 is not fixed to the rearsurface member 30.

The rear surface member 30 comprises the mounting rib 38 to which theprotruding portion 58 of the support plate 50 is attached, theconnection rib 36 to which the mounting rib 38 is connected, and theouter rib 32A and the inner rib 32B connected to each other by theconnection rib 36. Therefore, the rear surface member 30 is stiffened bythe frame-shaped outer rib 32A and inner rib 32B.

In the radiation detection device 10, as shown in FIG. 4, theintermittent portions 32BA and 32BB and the through holes 32AA and 32ABas opening portions, through which the battery 100 as an externallyinserted member is inserted, are formed in the outer rib 32A and theinner rib 32B. The opening connection rib 36B is formed at both ends ofthe opening portions 30A and 30B in the rear surface member 30 formed asdescribed above. Therefore, since the opening portions 30A and 30B arereinforced, the opening portions 30A and 30B are hardly deformed.

The mounting rib 38 is connected to the opening connection rib 36B, andthe support plate 50 is bonded to the mounting hole formed by thismounting rib 38. Therefore, the opening portions 30A and 30B arereinforced. In addition, since the protection rib 56D is formed on thesupport plate 50, the battery 100 inserted through the opening portions30A and 30B is protected.

The opening portions 30A and 30B are formed at the central portion ofthe rear surface member 30, that is, on the center lines CL1 and CL2.Therefore, compared with a case where the opening portion is formed inthe vicinity of the corner portion of the rear surface member 30, theinfluence in a case where an impact is applied to the corner portion ishardly received. For this reason, the opening portions are hardlydeformed.

The opening portions 30A and 30B are formed on two sides adjacent toeach other in the rear surface member 30. Therefore, as shown in FIG. 7,interference between the battery 100 and the signal processing unit 62Aand the gate line driver 62B on the control substrate 60, which areprovided along the two adjacent sides of the support plate 50, issuppressed. In addition, interference between the battery 100 and theflexible cables 46A and 46B connected to the signal processing unit 62Aand the gate line driver 62B is suppressed.

In the radiation detection device 10, as shown in FIGS. 2 and 3, thebottom plate 34 of the rear surface member 30 is fixed to the doubleframe 32 using a screw or the like. Therefore, by removing the screw,the signal processing unit 62A, the gate line driver 62B, the imagememory 62C, the controller 62D, and the like on the control substrate 60can be replaced or maintenance therefor can be performed. In addition,the double frame 32 and the bottom plate 34 can be integrally formed. Inthis case, the stiffness of the double frame 32 can be further improved.

In the radiation detection device 10, the double frame 32 in the rearsurface member 30 is gradually raised from the bottom surface onto whichthe bottom plate 34 is fitted to the outer edge portion in the directionof the front surface member 20, and the raised portion is the outer rib32A. Therefore, for example, in the case of inserting the radiationdetection device 10 between the bed and the patient, a situation inwhich the outer rib 32A is caught on a sheet or clothes is suppressed.As a result, the workability is improved.

A packing (not shown) is disposed between the front surface member 20and the surface of the outer rib 32A, which faces the front surfacemember 20, in the rear surface member 30, so that the internal spaceformed between the front surface member 20 and the rear surface member30 is a watertight space. Therefore, it is possible to protect thesupport plate 50 formed of a MgLi alloy having lower corrosionresistance than a Mg alloy.

In the radiation detection device 10, a side, which is a side along theshort side of the radiation detection device 10 (that is, a side alongthe Y direction) and on which the opening portion 30A is not formed,among the sides of the inner rib 32B is disposed such that theseparation distance from the outer rib 32A is larger than those of theother sides. Therefore, compared with a case where the separationdistance is the same as those of the other sides, the effect ofsuppressing deformation with respect to the impact along the X directionis enhanced.

In the radiation detection device 10, the opening portions 30A and 30Bthrough which the battery 100 is inserted are formed on the side surfaceof the rear surface member 30. Therefore, for example, in a case wherethe radiation detection device 10 is used in a state in which theradiation detection device 10 is attached to the imaging table, thebattery 100 and the imaging table are not easily caught with each other,so that the imaging table is easily ejected.

On the other hand, for example, in a case where an opening portion forinstalling the battery 100 is formed on the back surface of the rearsurface member 30, the battery cover or the like may protrude from theback surface to be caught with the imaging table. In a case where theopening portion for the battery is provided on the back surface whichoften contacts various places, such as a work table and a bed, dust orthe like is likely to clog a gap between the battery and the rearsurface member 30.

In the present embodiment, the gate line driver 62B and the signalprocessing unit 62A are disposed so as to be in direct contact with thesupport plate 50 without using a mount member, such as a resin.Therefore, since the heat emitted from the gate line driver 62B and thesignal processing unit 62A is dissipated to the support plate 50, thedurability of the gate line driver 62B and the signal processing unit62A is improved. In addition, local heating of the inside of theradiation detection device 10 is suppressed.

Other Embodiments

In the above embodiment, as shown in FIG. 4, the connection rib 36extends in a direction approximately perpendicular to the outer rib 32Aand the inner rib 32B. However, the embodiment of the invention is notlimited thereto. For example, as in the case of a connection rib 36Cshown in FIG. 8, a connection rib may be provided so as to extend in adirection crossing the outer rib 32A and the inner rib 32B so that atriangle is formed by the connection rib 36C and the outer rib 32A orthe inner rib 32B. In this case, since the outer rib 32A, the inner rib32B, and the connection rib 36C form a truss structure, it is possibleto increase the stiffness of the double frame 32.

In the above embodiment, the connection rib 36 is “bonded” to the outerrib 32A and the inner rib 32B. However, the embodiment of the inventionis not limited thereto. For example, a gap may be provided between theconnection rib 36 and the inner rib 32B. The size of the gap ispreferably such that the gap is closed in a case where an external forceis applied to the outer rib 32A to bring the connection rib 36 and theinner rib 32B into contact with each other. In this case, the externalforce can be transmitted to the inner rib 32B.

In a case where it is necessary to increase the gap between theconnection rib 36 and the inner rib 32B, for example, the connection rib36 is formed thick, so that the external force applied to the outer rib32A is transmitted from the connection rib 36 to the rear surface side(back side of the sheet in FIG. 4) of the connection rib 36 in thedouble frame 32. By forming the gap in this manner, various wirings inthe radiation detection panel 40 or the control substrate 60 can bedisposed inside the double frame, that is, between the outer rib 32A andthe inner rib 32B. This can improve the degree of freedom in wiringarrangement.

In addition, in order to improve the degree of freedom in wiringarrangement, at least one of the inner rib 32B and the connection rib 36may be partially lowered or cut away to form a defect portion, and thewiring may be made to pass through the defect portion. Instead of or inaddition to the defect portion, a through hole may be formed in theinner rib 32B and the connection rib 36, and the wiring may be made topass through the through hole.

In the above embodiment, as shown in FIG. 4, the thickness H2 of theinner rib 32B is set to be smaller than the thickness H1 of the outerrib 32A. However, the embodiment of the invention is not limitedthereto. For example, as in the case of an inner rib 32D shown in FIG.9, the inner rib may have the same thickness as the outer rib 32A. Inthis case, the stiffness of the double frame 32 can be improved.Alternatively, the width H3 of the double frame 32 can be reduced whilemaintaining the stiffness of the double frame 32. By reducing the widthH3 of the double frame 32, for example, the sizes of the support plate50 and the radiation detection panel 40 can be increased to increase thedetectable radiation dose.

In the above embodiment, as shown in FIG. 4, the inner rib 32B on theshort side where the opening portion 30A is not formed is disposed suchthat the separation distance from the outer rib 32A is larger than thatin the case of the inner rib 32B on the other sides. However, theembodiment of the invention is not limited thereto. For example, asshown in FIG. 9, the separation distance between the inner rib 32D andthe outer rib 32A on the short side where the opening portion 30A is notformed may be the same as the separation distance between the inner rib32D and the outer rib 32A on the other sides. In this case, it ispreferable to provide the oblique portion 32C at both ends of the innerrib 32D on the short side where the opening portion 30A is not formed.

In the embodiment shown in FIG. 9, the thick inner rib 32D may bereplaced with the thin inner rib 32B. Alternatively, the separationdistance between the thick inner rib 32D and the outer rib 32A on theshort side where the opening portion 30A is not formed may be largerthan the separation distance between the inner rib 32D and the outer rib32A on the other sides.

In the above embodiment, as shown in FIG. 1, the opening portions 30Aand 30B through which the battery 100 is inserted are formed on theadjacent side surfaces of the rear surface member 30. However, theembodiment of the invention is not limited thereto. For example, asshown in FIG. 10, the opening portion 30A may be formed on only oneshort side of the rear surface member 30. Alternatively, the openingportions 30A and 30C may be formed on two short sides facing each other.

Alternatively, as shown in FIG. 11, two opening portions 30D and 30E maybe formed on only one long side of the rear surface member 30.Alternatively, although not shown, one opening portion may be providedon only one long side of the rear surface member 30.

In addition, as in the case of an opening portion 30F shown in FIG. 12,an opening portion may be provided not on the side surface of the rearsurface member 30 but on the rear surface thereof. In the embodimenthaving two opening portions, one battery may be an externally insertedbattery, and the other battery may be a built-in battery. The built-inbattery comprises a terminal, and is charged by connecting a chargingcable from the outside. As components inserted through the openingportion, not only the battery but also a memory card, a communicationdevice, and the like can be appropriately adopted.

In the above embodiment, the outer rib 32A and the inner rib 32B areformed in a frame shape. However, the embodiment of the invention is notlimited thereto. For example, by forming at least one of the outer rib32A or the inner rib 32B only in the corner portion of the rear surfacemember 30, it is possible to efficiently protect the corner portion thatis susceptible to collision and deformation.

Alternatively, the outer rib 32A and the inner rib 32B may be partiallyformed in a part of the side surface along the X and Y directionswithout being limited to the corner portion of the rear surface member30. Since the stiffness of the part is also increased by partiallyforming the outer rib 32A and the inner rib 32B, the effect ofprotecting the radiation detection panel 40 can be obtained.

In the above embodiment, as shown in FIG. 2, the wall surface of thesupport post 52 is formed perpendicular to the support plate 50.However, the embodiment of the invention is not limited thereto. Forexample, as in the case of a support post 52B shown in FIG. 13, asupport post may be formed such that the thickness of the support postgradually increases from the distal end of the support post 52B towardthe support plate 50. In this manner, since the strength is improvedcompared with the support post 52 and the draft after molding isobtained, it is possible to enhance the manufacturing efficiency. Thedraft angle is preferably about 6° with respect to the normal directionof the support plate 50.

Alternatively, as in the case of a support post 52C shown in FIG. 14, asupport post may be formed such that the thickness of the support postgradually increases toward the support plate 50 from an intermediateportion in a height direction along the axial direction. In this manner,it is possible to reinforce the root portion of the support post 52C onwhich stress is easily concentrated while suppressing an increase in theweight of the entire support plate 50.

In the above embodiment, as shown in FIG. 2, the thickness of thereinforcing rib 56A along the axial direction of the support post 52 isfixed. However, the embodiment of the invention is not limited thereto.For example, as in the case of a reinforcing rib 56E shown in FIG. 15,the thickness of a reinforcing rib along the axial direction of thesupport post 52 may be gradually increased at a place of connection withthe support post 52. In this case, in a case where a load is input fromthe support plate 50 to the reinforcing rib 56E, the resistance againstbending moment and shear force acting on the boundary between thereinforcing rib 56E and the support post 52 is increased. Therefore, theload can be efficiently transmitted to the support post 52.

The configuration in which the thickness is gradually increased alongthe axial direction of the support post 52 at the place of connectionwith the support post 52 as described above can also be applied to thereinforcing rib 56B.

In the above embodiment, as shown in FIG. 2, the inside of the tubularsupport post 52 is hollow. However, the embodiment of the invention isnot limited thereto. For example, as shown in FIG. 16, an innerreinforcing rib 56F may be bridged between the inner walls of thesupport post 52. In this case, the buckling of the support post 52 canbe suppressed.

In addition, as shown by the broken line in FIG. 5, the innerreinforcing rib 56F is preferably disposed on the extension line of thereinforcing rib 56A. In this case, deformation of the support post 52due to the load transmitted from the reinforcing rib 56A is suppressed.

In the above embodiment, the support post 52 is formed integrally withthe support plate 50, and is formed in a tubular shape in which theaxial direction is the out-of-plane direction (direction perpendicularto the in-plane direction) of the support plate 50. However, theembodiment of the invention is not limited thereto.

As an example, as in the case of a support post 52D shown in FIG. 17, asupport post and the support plate 50 may be provided as separatebodies. In this case, the reinforcing ribs 56A and 56B may be formedintegrally with the support post 52D or may be formed as separatebodies. In a case where the reinforcing ribs 56A and 56B and the supportpost 52D are separate bodies, the reinforcing ribs 56A and 56B and thesupport post 52D are fixed by bonding. It is preferable that the supportpost 52D and the reinforcing ribs 56A and 56B are bonded to the supportplate 50.

As another example, as in the case of a support post 52E shown in FIG.18, a support post may be formed such that the axial direction of thesupport post follows the in-plane direction of the support plate 50.

As still another example, as in the case of a support post 52F shown inFIG. 19, a support post may be formed integrally with the bottom plate34 of the rear surface member 30.

Also by the support posts 52D, 52E, and 52F, in a case where a load inthe out-of-plane direction acts on the transmission plate 22 and theradiation detection panel 40, it is possible to stand the load. Theconfigurations of the support posts 52D, 52E, and 52F can also beapplied to the support post 54 shown in FIG. 5.

In the case of providing the support post and the support plate 50 asseparate bodies, the support post can be formed of various materials. Asthe support post, metal-based materials, such as an Al alloy and a Mgalloy, can be used as an example.

As another example, it is possible to use resin materials, such asacrylonitrile butadiene styrene (ABS) resin, polycarbonate (PC) resin,modified-polyphenyleneether (PPE) resin, polyethylene (PE) resin, highdensity polyethylene (HDPE) resin, polypropylene (PP) resin,polyoxymethylene (POM) resin, liquid crystal polymer (LCP) resin, andpolyetheretherketone (PEEK) resin.

As still another example, it is possible to use composite resinmaterials (reinforced plastics) reinforced by adding glass fiber,cellulose nanofiber, talc (calcium-based reinforcing material),magnesium fiber, and the like to the resin materials. As still anotherexample, a carbon material, fiber-reinforced plastics (FRP), and thelike can be used.

In the above embodiment, the two support posts 52 and 54 havingdifferent shapes are disposed on the support plate 50. However, theembodiment of the invention is not limited thereto. For example, asshown in FIG. 20, only the support post 52 having an approximatelyregular hexagonal shape may be used. In such a case, it is preferablethat the sides 52A of the support posts 52 adjacent to each other aredisposed so as to face each other.

In the above embodiment, the support posts 52 and 54 are formed in ahexagonal shape. However, the embodiment of the invention is not limitedthereto. For example, as in a support post 52G shown in FIG. 21, asupport post may have an octagonal shape. Also in such a case, it ispreferable that sides 52GA of the support posts 52G adjacent to eachother are disposed so as to face each other. The support post can becircular as well as polygonal. As described above, the invention can beimplemented in various forms.

What is claimed is:
 1. A radiation detection device, comprising: aradiation detection panel that detects radiation; a support plate whichis formed of a MgLi alloy and to which the radiation detection panel isfixed in contact with the support plate; a plurality of tubular supportposts that are formed in contact with a surface of the support plate notfacing the radiation detection panel; and a housing in which theradiation detection panel, the support plate, and the support posts arehoused and which is disposed in contact with the support posts.
 2. Theradiation detection device according to claim 1, wherein the supportposts are polygonal, and at least some of the support posts adjacent toeach other are disposed such that sides of the support posts face eachother.
 3. The radiation detection device according to claim 1, whereineach of the support posts is formed so as to have an axial directionalong an out-of-plane direction of the support plate.
 4. The radiationdetection device according to claim 1, wherein a thickness of each ofthe support posts gradually increases from a distal end to a rootportion near the support plate.
 5. The radiation detection deviceaccording to claim 1, wherein the support posts are formed integrallywith the support plate using the same material as the support plate. 6.The radiation detection device according to claim 1, wherein areinforcing rib is bridged between the support posts so as to be incontact with the surface of the support plate not facing the radiationdetection panel.
 7. The radiation detection device according to claim 6,wherein both end portions of the reinforcing rib are formed such thatthicknesses thereof along axial directions of the support postsgradually increase toward the support posts.
 8. The radiation detectiondevice according to claim 6, wherein an inner reinforcing rib is bridgedbetween inner walls of the support post.
 9. The radiation detectiondevice according to claim 8, wherein the inner reinforcing rib isdisposed on an extension line of the reinforcing rib.
 10. The radiationdetection device according to claim 1, wherein an outer peripheralportion of the support plate is bonded to the housing.
 11. The radiationdetection device according to claim 10, wherein a frame-shaped outerperipheral portion reinforcing rib is provided in the outer peripheralportion of the support plate, and the outer peripheral portionreinforcing rib is bonded to the housing.
 12. The radiation detectiondevice according to claim 10, wherein the housing comprises: a mountingrib to which the outer peripheral portion of the support plate isattached; a connection rib to which the mounting rib is connected; andan outer rib and an inner rib that are connected to each other by theconnection rib and are formed along an outer edge of the housing.